1. Field of the Invention:
The present invention relates to a fluid pressure brake booster for use in motor vehicles.
2. Description of the Prior Art:
Brakes for use in motor vehicles include a fluid pressure brake booster for assisting the brake in producing increased braking power when the brake is actuated. One conventional fluid pressure brake booster, as disclosed in Japanese Laid-Open Patent Publication No. 57-198157, includes an accumulator for storing a fluid pressure for selective use, the accumulator being held in communication with a booster housing, and a valve device actuatable for controlling fluid communication from the accumulator to a power chamber to allow a fluid pressure to act on a piston in the power chamber for thereby forcing the fluid from the booster housing into a braking circuit.
With the conventional fluid pressure brake booster, a master cylinder and the booster housing are of an integral construction with equal cylinder diameters. The pistons in the master cylinder and booster have annular grooves defined in outer peripheral surfaces thereof and communicating respectively with a reservoir and the accumulator. The formation of the annular grooves in the pistons however is disadvantageous in that the fluid pressure brake booster is axially elongated in overall construction.